Projectors equipped with LEDs, in which each LED has a corresponding red (R), green (G) or blue (B), are known. Typically, LEDs have a property by which luminance (illuminance) decreases in response to an increase in the temperature. In order to realize a projector having higher luminance, the LEDs must therefore be cooled to prevent a reduction of luminance (illuminance).
In Patent Document 1, a liquid cooling system is described in which each LED having a corresponding red, green or blue color is cooled.
In the liquid cooling system described in Patent Document 1, attention is given to the difference in the amount of heat generated by the LEDs of each color, with cooling proceeding in order from LEDs having a greater amount of generated heat. More specifically, this cooling system includes: a pump, a single flow path by which a coolant that is supplied from this pump circulates, a radiator that cools the coolant that has flowed within this flow path, and a fan that supplies cooling air to this radiator.
The above-described flow path is formed so as to transfer heat-conductive parts provided in each red, green and blue, starting with the LED that generates the largest amount of heat and finishing with the LED that generates the least amount of heat. Normally, the amount of heat generated by a green LED is greatest, followed by the amount of heat generated by a blue LED. The amount of heat generated by a red LED is the smallest.
In the above-described liquid cooling system, coolant that is supplied from the pump passes through the heat-conductive parts of the green LED for which the amount of generated heat is greatest. The green LED is cooled here by the heat exchange that takes place between the heat-conductive part and the coolant, but the temperature of the coolant is also raised by this heat exchange.
The coolant that has passed by way of the heat-conductive part of the green LED passes through the heat-conductive part of the blue LED, and then passes through the heat-conductive part of the red LED. When the coolant passes through each of the heat-conductive parts of the blue LED and red LED, heat exchange takes place between the heat-conductive parts and the coolant, by which the blue LED and red LED are cooled but the temperature of the coolant is also raised by the heat exchange.
The coolant that has passed through the heat-conductive part of the red LED, after being cooled in the radiator, is returned to the pump.
In Patent Document 2, a configuration is described in which a cooling system that cools the light source part in which the amount of heat that has been generated is greatest is provided separately from a cooling system that cools other light source parts. By means of this configuration, the light source part in which a cooling system that cools the light source part in which the amount of heat that has been generated is greatest and other light source parts are each cooled by independent cooling systems, whereby the light source parts can be effectively cooled.